NEW BARREL, break in 2 cast

[XWrench3]

just had a new remington barrel installed on my 700 300 win mag. how many jacketed rounds should i have to run through it in order to knock down the rough stuff (machining marks) so i can shoot cast boolits without a lot of leading? at this point, i am running boolits lubed with l.l.a. becasue i dont have a lube/sizer yet.

[nicholst55]

I would pan lube if I didn't have a lube/sizer - especially for rifle boolits. Apply your gas checks first, then stand them up in the pan; you can either pour the melted lube in, or else just stand your boolits up in the melted lube. Set the pan in the freezer for 15-20 minutes, then pop the whole mess out of the pan and 'punch' the boolits out from the bottom side to the top.

LLA is a pretty marginal lube, and normally only suitable for low pressure handgun loads - at least, that's what I'm told by people with W-A-Y more experience than I have with it.

[JesterGrin_1]

Here is a thread on Break In. http://castboolits.gunloads.com/show...arrel+break-in

[missionary5155]

Good morning
Save the jackerted "Thangs" for stopping rampaging Toyotas !
My standard proceedure for any new barrel is to ...
1st run a very tight patch through the barrel and get an idea how rough it is. Compare that to a well shot barrel and you will get the idea.
Next if the barrel exibits rough, snaggy areas with a TIGHT patch I use a .001+ oversize WW boolit lubed with fine valve grinding compound shot with a mild load of Unique to get about 1300 fps. Shoot 5 and clean barrel . Run another TIGHT patch. If still rough or with snags, loosespots, or tight spots fire another 5 lubed with Fine compound. Clean and check with the TIGHT patch.
If consistent smoothness is felt (no snags, loosespots, tightspots) Then I fire 5 boolits lubed with metal polish.
If the barrel was smooth to start with I still fire the 5 boolits lubed with metal polish . This really slicks it up.
There are all sorts of methods people use. You can buy fire lap kits. I found this simple and cheap procedure to produce what I was looking for.

[Molly]

Good morning
>Then I fire 5 boolits lubed with metal polish.
If the barrel was smooth to start with I still fire the 5 boolits lubed with metal polish . This really slicks it up.

Personally, I just ASSUME than any new barrel is going to be less than perfect for cast boolits, and fire polish it a few rounds that are lubed with J-B compound. If I have a particularly rough example, I'll even use j-word bullets at low velocity to polish faster. It'll turn a rough bore into a mirror bright bore in a hurry, and make it more uniform at the same time. Stop when the bore doesn't get any brighter / shinier with a few more shots. Then clean well before starting your real tests. Best and quickest way I know to break in a new barrel.

[XWrench3]

well, the path i have chosen is run 80 j bullets through it, cleaning every 5 rounds. then 12 abrasive (600 grit) impregnated bullets cleaning every 3 rounds, then 20 more 220g j bullets. i have all but the last 20 done now. if that isnt sufficient, then i guess it will just have to stay rough! LOL!

[Molly]

well, the path i have chosen is run 80 j bullets through it, cleaning every 5 rounds. then 12 abrasive (600 grit) impregnated bullets cleaning every 3 rounds, then 20 more 220g j bullets. i have all but the last 20 done now. if that isnt sufficient, then i guess it will just have to stay rough! LOL!

Well, that ought to take care of any tight spots in the bore all right, but you just might end up with a bore that isn't very shiny. If you do, a few rounds with JB compound will take care of it.

[JesterGrin_1]

JB Compound?

[Molly]

JB Compound?

Sorry for the assumption that everyone knows about J-B Compound. It's a VERY mild abrasive/polish that is sold for the purpose of cleaning copper jacketed fouling out of fouled bores without damaging the steel bore. Another web site describes it as

(quote)
The original time-proven formula developed by Jim Brobst and produced under exclusive license. J-B has been getting burned-on caked-in powder residue and copper jacket fouling out of gun barrels since the 1960’s and hasn’t damaged an inch of rifling yet. Today J-B once again proves itself a champion by the way it easily cleans the dirtiest moly-fouled barrels.
(end quote)


You can get it (and more description) from Brownells at <www.brownells.com/..../J_B_reg__NON_EMBEDDING_BORE_CLEANING_COMPOUND>

[JesterGrin_1]

Well By Golly Molly lol. I think this is it? http://www.brownells.com/.aspx/sid=4...ompound__2_oz_

[John 242]

...fire polish it a few rounds that are lubed with J-B compound.

Molly, when you say 'lubed' what do you mean? I take it that the J-B compound is a paste, but how do you apply it to the bullet? Do you let it dry or simply load the bullet into the case after smearing it on?
Thanks,
John

[Molly]

Molly, when you say 'lubed' what do you mean? I take it that the J-B compound is a paste, but how do you apply it to the bullet? Do you let it dry or simply load the bullet into the case after smearing it on?
Thanks,
John

Hi John,
Sometimes when I'm only wanting to assemble five or six experimental rounds, I will apply the bullet lube by hand, smearing it into the lube grooves with my fingers and then seating the bulelt normally.

You can apply J-B compound the same way, before the bullet is seated. Or you can use the lazy man's technique; Get a bore mop that fits your gun, and work J-B compound into it pretty well. Then remove the bolt and run the bore mop down the barrel two or three times to be sure it's completely coated. Then chamber and fire a light load in the 1400 - 1500 FPS range. Repeat about five or six times, then run a solvent soaked patch through the barrel, and follow with a dry patch. This will let you take a look at your progress. Stop when you like what you see. If it's still kinda gray (as opposed to mirror bright), just repeat until you are happy.

One word of caution: The J-B compound is NOT a lubricant. It has to increase friction considerably in order to polish. Higher friction means higher pressures. DO NOT try this with anything near factory or full power loads, as you will elevate pressures well into the danger area. That's why I specified use of a light load only.

[XWrench3]

well, i can not tell how bright and shiney it is. i have "old man eyes". without glasses, it is just a blur. with glasses, i can see the first inch or so, then everything beyond is a blur. the only way for me to really tell would be with a borescope. and then, only if i could see that! LOL! i had thought about trying to ploish the bore with simichrome or jb compound, but i read somewhere that to smooth of a bore is not a good thing for cast boolits. of course, the other option to get a SHINEY bore is paper patching. a scary thought just went through my head. and i have no idea if it would work or not. paper patch with wet or dry paper. start @ 600 and work your way to 2000. of course, that could be a really good way to sand the rifling right out of a barrel as well. i really think i will just stay with what i have. one of these days, i will find a really good deal on jacketed bullets again. weather at a garage sale, gunbroker, or midways blems. and i can shoot 200-500 more through it. the old barrel was definitly smoothed out, haveing well over 5,000 rounds of jacketed bullets through it, with countless cast.

[Molly]

well, i can not tell how bright and shiney it is. i have "old man eyes". without glasses, it is just a blur. with glasses, i can see the first inch or so, then everything beyond is a blur. the only way for me to really tell would be with a borescope. and then, only if i could see that! LOL!

Believe me, I DO understand about old eyes.

i had thought about trying to ploish the bore with simichrome or jb compound, but i read somewhere that to smooth of a bore is not a good thing for cast boolits.

I've heard the same thing, but I've never read where someone actually polished a bore and had worse accuracy as a result. I think it's just another old wife's tale. Every report I ever read of actual results found the more polished or lapped bore gave better results.

of course, the other option to get a SHINEY bore is paper patching. a scary thought just went through my head. and i have no idea if it would work or not. paper patch with wet or dry paper. start @ 600 and work your way to 2000.

Not a bad thought, but I'd just smear some J-B on about five of them and see what I got from that.

of course, that could be a really good way to sand the rifling right out of a barrel as well.

Well, I never heard of J-B causing any measurable bore wear. I had a friend once who decided to see just how abrasive it was, on the logic that it has to be at least a little abrasive to clean so well. He got a bit of cotton rag and put some J-B on it, and started scrubbing on a little piece of mild steel. He was a stubborn cuss, and kept on going despite the apparent lack of any polishing effect at first. It took him scrubbing all summer before he began to see even a very slight polishing effect. I think your bore is safe.